Temperature trend controlled cooling system

ABSTRACT

An information handling system (IHS) temperature control system includes a cooling system, a controller coupled to the cooling system, and an IHS coupled to the controller. The IHS includes a temperature status reporting engine that is configured to determine a first temperature of the IHS and determine a second temperature of the IHS subsequent to determining the first temperature. In response to the second temperature being above a first predetermined temperature range, the temperature status reporting engine provides a first signal to the controller to increase cooling provided by the cooling system if the first temperature and the second temperature indicate that a temperature trend of the IHS is not decreasing, and provides a second signal to the controller to maintain cooling provided by the cooling system if the first temperature and the second temperature indicate that the temperature trend of the IHS is decreasing.

BACKGROUND

The present disclosure relates generally to information handlingsystems, and more particularly to controlling a cooling system in aninformation handling system using temperature trends.

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option is an information handling system (IHS). An IHS generallyprocesses, compiles, stores, and/or communicates information or data forbusiness, personal, or other purposes. Because technology andinformation handling needs and requirements may vary between differentapplications, IHSs may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in IHSs allowfor IHSs to be general or configured for a specific user or specific usesuch as financial transaction processing, airline reservations,enterprise data storage, or global communications. In addition, IHSs mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

IHS chassis or racks are sometimes provided to house a plurality ofIHSs, and typically include a cooling system for cooling those IHSs. Forexample, an IHS chassis may house a plurality of a server IHSs, switchIHSs or other networking IHSs, storage IHSs, and/or a variety of otherIHSs known in the art, as well as a cooling system for cooling thoseIHSs. A chassis management controller may be coupled to the IHSs and thecooling systems, and may be configured to receive a temperature statusfrom each of the IHSs and use that temperature status to control thecooling system. The temperature status reported by each of the IHSs isbased on temperature thresholds, with the reported temperature statuschanging when the temperature of the IHS passes those thresholds. Theuse of temperature thresholds to report a temperature status raises anumber of issues, as the conventional actions taken in response toconventionally reported temperature thresholds can result inover-operation of the cooling system when it is not needed by the IHSs,which unnecessarily increases power consumption, component degradation,and noise.

Accordingly, it would be desirable to provide for improved control ofcooling systems.

SUMMARY

According to one embodiment, an information handling system (IHS)temperature control system includes a cooling system; a controllercoupled to the cooling system; and an IHS coupled to the controller,wherein the IHS includes a temperature status reporting engine that isconfigured to: determine a first temperature of the IHS; determine asecond temperature of the IHS subsequent to determining the firsttemperature; and in response to the second temperature being above afirst predetermined temperature range, provide a first signal to thecontroller to increase cooling provided by the cooling system if thefirst temperature and the second temperature indicate that a temperaturetrend of the IHS is not decreasing, and provide a second signal to thecontroller to maintain cooling provided by the cooling system if thefirst temperature and the second temperature indicate that thetemperature trend of the IHS is decreasing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating an embodiment of an informationhandling system.

FIG. 2 is a schematic view illustrating an embodiment of an IHStemperature control system.

FIG. 3 a is a flow chart illustrating an embodiment of a prior artmethod for providing temperature control.

FIG. 3 b is a chart illustrating an embodiment of temperature controlusing the prior art method of FIG. 3 a.

FIG. 4 a is a flow chart illustrating an embodiment of a method forproviding temperature control according to the teachings of the presentdisclosure.

FIG. 4 b is a chart illustrating an embodiment of temperature controlusing the method of FIG. 4 a.

FIG. 4 c is a chart illustrating an embodiment of temperature controlusing the method of FIG. 4 a.

FIG. 5 is a flow chart illustrating an embodiment of a method forproviding temperature control according to the teachings of the presentdisclosure.

DETAILED DESCRIPTION

For purposes of this disclosure, an IHS may include any instrumentalityor aggregate of instrumentalities operable to compute, classify,process, transmit, receive, retrieve, originate, switch, store, display,manifest, detect, record, reproduce, handle, or utilize any form ofinformation, intelligence, or data for business, scientific, control,entertainment, or other purposes. For example, an IHS may be a personalcomputer, a PDA, a consumer electronic device, a display device ormonitor, a network server or storage device, a switch router or othernetwork communication device, or any other suitable device and may varyin size, shape, performance, functionality, and price. The IHS mayinclude memory, one or more processing resources such as a centralprocessing unit (CPU) or hardware or software control logic. Additionalcomponents of the IHS may include one or more storage devices, one ormore communications ports for communicating with external devices aswell as various input and output (I/O) devices, such as a keyboard, amouse, and a video display. The IHS may also include one or more busesoperable to transmit communications between the various hardwarecomponents.

In one embodiment, IHS 100, FIG. 1, includes a processor 102, which isconnected to a bus 104. Bus 104 serves as a connection between processor102 and other components of IHS 100. An input device 106 is coupled toprocessor 102 to provide input to processor 102. Examples of inputdevices may include keyboards, touchscreens, pointing devices such asmouses, trackballs, and trackpads, and/or a variety of other inputdevices known in the art. Programs and data are stored on a mass storagedevice 108, which is coupled to processor 102. Examples of mass storagedevices may include hard discs, optical disks, magneto-optical discs,solid-state storage devices, and/or a variety other mass storage devicesknown in the art. IHS 100 further includes a display 110, which iscoupled to processor 102 by a video controller 112. A system memory 114is coupled to processor 102 to provide the processor with fast storageto facilitate execution of computer programs by processor 102. Examplesof system memory may include random access memory (RAM) devices such asdynamic RAM (DRAM), synchronous DRAM (SDRAM), solid state memorydevices, and/or a variety of other memory devices known in the art. Inan embodiment, a chassis 116 houses some or all of the components of IHS100. It should be understood that other buses and intermediate circuitscan be deployed between the components described above and processor 102to facilitate interconnection between the components and the processor102. Furthermore, the IHS 100 may include networking devices forcommunicating with a network (e.g., a Local Area Network (LAN)).

Referring now to FIG. 2, an embodiment of an IHS temperature controlsystem 200 is illustrated. In the illustrated embodiment, the IHStemperature control system 200 includes an IHS rack 202 that houses thecomponents of the IHS temperature control system 200. However, in otherembodiment, the IHS rack 202 may be any IHS enclosure that is configuredto house IHSs, controllers, cooling systems, and/or other componentsknown in the art. Furthermore, in some embodiments, the IHS rack 200 maybe omitted. A plurality of IHSs 204 are located in the IHS rack 202 andeach of the IHSs 204 may be the IHS 100 discussed above with referenceto FIG. 1 or may include some or all of the components of the IHS 100.In the illustrated embodiment, the IHSs 204 include a plurality ofswitch IHSs 204 a, a plurality of server IHSs 204 b, and a plurality ofstorage IHSs 204 c. Each of the IHSs 204 and the IHS rack 202 mayinclude features for coupling, decoupling, securing, un-securing, and/orotherwise positioning the IHSs 204 in the IHS rack. In an embodiment,the switch IHSs 204 a may be, for example, Dell Networking MXL switchIHSs available from Dell Inc. of Round Rock, Tex., Dell PowerEdge M I/OAggregator switch IHSs available from Dell Inc., Dell PowerConnectM8024K switch IHSs available from Dell Inc., and/or a variety of otherswitch IHSs known in the art. In an embodiment, the server IHSs 204 bmay be Dell PowerEdge rack server IHSs available from Dell Inc., DellBlade servers available from Dell Inc., and/or a variety of other serverIHSs known in the art. In an embodiment, the storage IHSs may be DellEqualLogic storage IHSs available from Dell Inc., Dell PowerVaultstorage IHSs available from Dell Inc., and/or a variety of other storageIHSs known in the art. While a few examples of IHSs have been provided,any other IHS, as well as other heat producing devices including IHScomponents and/or non-IHS heat producing devices, will benefit from theteachings of the present disclosure and are envisioned as falling withinits scope.

Each of the IHSs 204 may include a processing system (e.g., theprocessor 102 discussed above with reference to FIG. 1) that is locatedin the IHS 204 and that is coupled to a memory system (e.g., the systemmemory 114 discussed above with reference to FIG. 1) that is located inthe IHS 204 and that includes instructions that, when executed by theprocessing system, cause the processing system to provide a temperaturestatus reporting engine 206 that is configured to perform the functionsof the temperature status reporting engines discussed below. Eachtemperature status reporting engine 206 in the IHSs 204 may be coupledto a temperature sensor 208 (e.g., through a coupling between thetemperature sensor 208 and the processing system in that IHS 204) thatis located in that IHS 204 and that is configured to measure atemperature of that IHS 204, a temperature of a component of that IHS204, and/or any temperature that is indicative of the thermal conditionsexperienced by that IHS 204. Thus, the temperature sensors 208 may beconfigured to measure an average temperature in their associated IHS204, the highest temperature component in their associated IHS 204,and/or any other temperature of their associated IHS that is known inthe art to dictate the cooling requirements of an IHS.

A chassis management controller 210 is located in the IHS rack 202 andmay be the IHS 100 discussed above with reference to FIG. 1 or mayinclude some or all of the components of the IHS 100. The chassismanagement controller 210 may include a processing system (e.g., theprocessor 102 discussed above with reference to FIG. 1) that is coupledto a memory system (e.g., the system memory 114 discussed above withreference to FIG. 1) that includes instructions that, when executed bythe processing system, cause the processing system to provide atemperature control engine 212 that is configured to perform thefunctions of the temperature control engines discussed below. Thechassis management controller 210 is coupled to each of the IHSs 204,and more specifically, in the illustrated embodiment, the temperaturecontrol engine 212 in the chassis management controller 210 is coupledto the temperature status reporting engines 206 in each of the IHSs 204(e.g., through a coupling between the processing system in the chassismanagement controller 210 and the processing systems in each of the IHSs204).

A cooling system 214 is located in the IHS rack 202 and, in theillustrated embodiment, includes a plurality of fans 216. The chassismanagement controller 210 is coupled to each of the plurality of fans216, and more specifically, in the illustrated embodiment, thetemperature control engine 212 in the chassis management controller 210is coupled to each of the fans 216 (e.g., through a coupling between theprocessing system in the chassis management controller 210 and a fancontroller in each of the fans 216). In the illustrated embodiment, thecooling system 214 is illustrated as providing a respective fan locatedadjacent each IHS 204. However, in other embodiments, any number,combination, and positioning of fans and IHSs may be provided and usedaccording to the teachings of the present disclosure. As discussedbelow, in some embodiments, groups of the IHSs may share one or more ofthe fans 216, and the chassis management controller 210 may communicatewith each of the IHSs 204 in the group to determine how to control thefans 216 associated with that group. In other embodiments, each IHS 204may communicate with the chassis management controller 210 to control arespective fan 216 that provides cooling to that IHS 204.

Referring now to FIG. 3 a, a prior art method 300 for providingtemperature control using the IHS temperature control system 200 of FIG.2 is illustrated. In the prior art method 300, the IHSs 204 usetemperature thresholds to determine a temperature status that is sent tothe chassis management controller 210. The prior art method 300 will bediscussed below with reference to a single IHS, but it should beunderstood each of the IHSs 204 is configured to perform the prior artmethod 300 during its operation. The prior art method 300 begins atblock 302 where the IHS 204 determines a current temperature. The priorart method 300 the proceeds to decision block 304 to determine whetherthe current temperature is less than or equal to 50° C. If at decisionblock 304 it is determined that the current temperature is not less thanor equal to 50° C., the prior art method 300 proceeds to decision block306 where it is determined whether the current temperature is greaterthan 50° C. and less than or equal to 70° C. If at decision block 306 itis determined that the current temperature is not greater than 50° C.and less than or equal to 70° C., the prior art method 300 proceeds todecision block 308 where it is determined whether the currenttemperature is greater than 70° C. and less than or equal to 80° C. Ifat decision block 308 it is determined that the current temperature isnot greater than 70° C. and less than or equal to 80° C., the prior artmethod 300 proceeds to decision block 310 where it is determined whetherthe current temperature is greater than 80° C. and less than or equal to85° C. Thus, the prior art method 300 involves each IHS 204 determiningwhen its current temperature has cross a plurality of temperaturethresholds (e.g., 50° C., 70° C., 80° C., and 85° C.).

The prior art method 300 includes a plurality of temperature statuses,and each of the IHSs 204 may send one of those temperature statuses whenits current temperature passes any of the temperature thresholdsdiscussed above. In the prior art method 300, a first temperature status(“TEMP STATUS 1”) corresponds to a below normal temperature reading, andis reported by the IHS 204 to the chassis management controller 210 atblock 312 in response to determining at decision block 304 that itscurrent temperature has not passed the 50° C. temperature threshold. Thechassis management controller 210 is configured to decrease the fanspeed of the fans 216 by 4% every 20 seconds in response to thereporting of a TEMP STATUS 1 from the IHS 204. A second temperaturestatus (“TEMP STATUS 2”) corresponds to a normal temperature reading,and is reported by the IHS 204 to the chassis management controller 210at block 314 in response to determining at decision block 306 that itscurrent temperature has passed the 50° C. threshold. The chassismanagement controller 210 is configured to make no changes to the fanspeed of the fans 216 in response to the reporting of a TEMP STATUS 2from the IHS 204. A third temperature status (“TEMP STATUS 3”)corresponds to a warning temperature reading, and is reported by the IHS204 to the chassis management controller 210 at block 316 in response todetermining at decision block 308 that its current temperature haspassed the 70° C. threshold. The chassis management controller 210 isconfigured to increase the fan speed of the fans 216 by 5% every 5seconds in response to the reporting of a TEMP STATUS 3 from the IHS204. A fourth temperature status (“TEMP STATUS 4”) corresponds to acritical temperature reading, and is reported by the IHS 204 to thechassis management controller 210 at block 318 in response todetermining at decision block 310 that its current temperature haspassed the 80° C. threshold. The chassis management controller 210 isconfigured to increase the fan speed of the fans 216 by 20% every 5seconds in response to the reporting of a TEMP STATUS 4 from the IHS204. A fifth temperature status (“TEMP STATUS 5”) corresponds to ashutdown temperature reading, and is reported by the IHS 204 to thechassis management controller 210 at block 320 in response todetermining at decision block 310 that its current temperature haspassed the 85° C. threshold. The chassis management controller 210 isconfigured to shut down the IHS 204 in response to the reporting of aTEMP STATUS 5 from the IHS 204.

Referring now to FIG. 3 b, a chart 322 is provided to illustrate thedeficiencies in the operation of the IHS temperature control system 200according to the prior art method 300 of FIG. 3 a. It has beendiscovered that when switch IHSs with relatively high power consumption(e.g., Dell Networking MXL switch IHSs, Dell PowerEdge M I/O Aggregatorswitch IHSs, and Dell PowerConnect M8024K switch IHSs, all availablefrom Dell Inc.) are included in the IHS temperature control system 200and operate according to the prior art method 300, the fans 216 mayoscillate between 30% pulse-width modulation (PWM) and 100% PWM forperiods of around 30 minutes, which creates power consumption issues,component degradation issues, and noise issues. The chart 322, withreference to the prior art method 300 and temperature status controlactions discussed above, illustrates this phenomenon. The chart 322includes a plurality of rows separate into three columns—a temperaturedetermined (e.g., the “current temperature” of the IHS 204 discussedabove), a temperature status reported by the IHS 204 in response to thedetermined temperature passing a threshold, and a fan speed (in % PWM)that results when that temperature status is reported to the chassismanagement controller 210.

With reference to the chart 322 beginning at the first row, the IHS 204is shown in a situation in which the determined temperature is 68° C.,69° C., and 70° C. (i.e., the current temperature of the IHS 204 isdetermined to be greater than 50° C. and less than or equal to 70° C. atdecision block 306) in successive iterations of the prior art method300, which provides for a reported second temperature status (“TEMPSTATUS 2”) at block 314. In response the reported second temperaturestatus, the chassis management controller 210 makes no changes to thefan speed of the fans 216 in any of those iterations, providing for afan speed of 30% PWM in the illustrated embodiment.

The IHS 204 then determines temperatures of 71° C. and 72° C. (i.e., thecurrent temperature of the IHS 204 is determined to be greater than 70°C. and less than or equal to 80° C. at decision block 308) in successiveiterations of the prior art method 300, which provides for a reportedthird temperature status (“TEMP STATUS 3”) at block 316 when thedetermined temperature passes the 50° C. threshold. In response to thereported third temperature status, the chassis management controller 210increases the fan speed of the fans 216 by 5% every 5 seconds, providingfor an increase in the fan speeds to 35% PWM and 50% PWM in theillustrated embodiment.

The IHS 204 then determines a temperature of 72° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 308) in the followingiteration of the prior art method 300, which provided for a reportedthird temperature status (“TEMP STATUS 3”). In response, the chassismanagement controller 210 continues to increase the fan speed of thefans 216 by 5% every 5 seconds, providing for a fan speed of 70% PWM inthe illustrated embodiment. The IHS 204 then determines a temperature of71° C. (i.e., the current temperature of the IHS 204 is determined to begreater than 70° C. and less than or equal to 80° C. at decision block308) in the following iteration of the prior art method 300, whichprovides for the reported third temperature status (“TEMP STATUS 3”) atblock 316. In response to the reported third temperature status, thechassis management controller 210 increases the fan speed of the fans216 by 5% every 5 seconds, providing for a fan speed of 100% PWM in thatiteration in the illustrated embodiment. Thus, while the temperature ofthe IHS 204 stabilized (i.e., at 72° C.) and then began to decrease(i.e., from at 72° C. to 71° C.), the prior art method 300 has resultedin the increasing of the fan speed of the fans 216 from 70% PWM to 100%PWM.

The chart 322 then illustrates how in successive iterations of the priorart method 300 the IHS 204 determines temperatures between 70° C. and51° C. (i.e., the current temperature of the IHS 204 is determined to begreater than 50° C. and less than or equal to 70° C. at decision block306), which provides for a reported second temperature status (“TEMPSTATUS 2”) at block 314 when the determined temperature passed the 70°C. threshold. In response to the reported second temperature status, thechassis management controller 210 makes no changes to the fan speed ofthe fans 216, providing for a fan speed of 100% PWM throughout thattemperature range in the illustrated embodiment.

The IHS 204 then goes on to determine temperatures of 50° C., 49° C.,and 48° C. (i.e., the current temperature of the IHS 204 is determinedto be less than or equal to 50° C. at decision block 304) in successiveiterations of the prior art method 300, which provides for a reportedfirst temperature status (“TEMP STATUS 1”) at block 312 when thedetermined temperature passed the 50° C. threshold. In response to thereported first temperature status, the chassis management controller 210decreases the fan speed of the fans 216 by 4% every 20 seconds,providing for fan speeds of 96% PWM, 80% PWM, and 60% PWM in eachsuccessive iteration in the illustrated embodiment.

The IHS 204 then determines temperatures of 49° and 50° C. (i.e., thecurrent temperature of the IHS 204 is determined to be less than orequal to 50° C. at decision block 304) in successive iterations of theprior art method 300, which provides for the reported first temperaturestatus (“TEMP STATUS 1”) at block 312. In response to the reported firsttemperature status, the chassis management controller 210 continues todecrease the fan speed of the fans 216 by 4% every 20 seconds, providingfor fan speeds of 40% PWM and 30% PWM in the illustrated embodiment.Thus, while the temperature of the IHS 204 is increasing (i.e., from 48°C. to 50° C.), the prior art method 300 has continued to decrease thefan speed of the fans 216 from 60% PWM to 30% PWM. The IHS 204 thendetermines a temperature of 51° C. (i.e., the current temperature of theIHS 204 is determined to be greater than 50° C. and less than or equalto 70° C. at decision block 306), which provides for a reported secondtemperature status (“TEMP STATUS 2”) at block 314 when the determinedtemperature passed the 50° C. threshold. In response to the reportedsecond temperature status, the chassis management controller 210 makesno changes to the fan speed of the fans 216, providing for a fan speedof 30% PWM in successive iterations in the illustrated embodiment untilthe IHS 204 again passes the 70° C. threshold or the 50° C. threshold.

As can be seen, the prior art method 300 results in oscillations of thefan speed that may cause the cooling system to provide too much cooling(e.g., extended periods of fan speeds of 100% PWM in the illustratedembodiment), too little cooling (e.g., extended periods of fan speeds of30% PWM in the illustrated embodiment), and/or may result in a varietyof other cooling system oscillations known in the art. The presentdisclosure provides for control of the cooling system based ontemperature trends of the IHS 204, rather than the passing oftemperature thresholds that result in the deficiencies provided by theprior art method 300 discussed above.

Referring now to FIG. 4 a, an embodiment of a method 400 for providingtemperature control according to the teachings of the present disclosureis illustrated. In some embodiments, the method 400 may be performed byeach of the IHSs 204 and result in the control of all of the fans 216 bythe chassis management controller 210. For example, each of the IHSs 204may perform the method 400 to send a respective temperature status tothe chassis management controller 210, and the chassis managementcontroller 210 may control all of the fans 216 based on the temperaturestatus that indicates the highest temperature in any of the IHSs 204. Inother examples, the chassis management controller 210 may controlsubsets of the fans 216 based on the temperature statuses received fromsubsets of the IHSs 204. In other embodiments, the method 400 may beperformed by each of the IHSs 204 and result in the control of arespective fan 216 or set of fans 216 by the chassis managementcontroller 210. For example, each IHS 204 may be associated with arespective fan 216 that controls the cooling for that IHS 204, and thechassis management controller 210 may control that fan 216 based on thetemperature status received from that IHS 204. While a few examples havebeen provided, any combinations of IHSs, fans, and the control of fansusing signals from IHSs is envisioned as falling within the scope of thepresent disclosure. Furthermore, while the method 400 is described belowas being performed by a single IHS 204, each of the IHSs 204 may performthe method 400 at substantially the same time while remaining within thescope of the present disclosure.

The method begins at block 402 where a last temperature is set at 0. Inan embodiment, the IHS 204 includes a database or other memory structurein which a last temperature may be stored, and at block 402, thetemperature status reporting engine 206 in the IHS 204 stores a lasttemperature of 0° C. In other embodiments, the last temperature storedat block 402 may be temperatures other than 0° C., which may be selectedby a user, administrator, manufacturer, or other entity. The method 400then proceeds to block 404 where a current temperature is determined. Inan embodiment, the temperature status reporting engine 206 in the IHS204 retrieves or receives a temperature measured by the temperaturesensor 208 in that IHS 204 to determine the current temperature at block404. As discussed above, the current temperature determined at block 404may be a current temperature of the IHS 204, a current temperature of acomponent of the IHS 204, and/or any current temperature that isindicative of the current thermal conditions experienced by the IHS 204.Furthermore, the current temperature determined at block 404 may be anaverage temperature in IHS 204, the highest temperature component in theIHS 204, and/or any other temperature of the IHS 204 that is known inthe art to dictate the cooling requirements of an IHS.

The method 400 then proceeds to decision block 406 where it isdetermined whether the current temperature is in a first temperaturerange (e.g., less than or equal a first temperature T1 in theillustrated embodiment). In an embodiment, the temperature statusreporting engine 206 in the IHS 204 compares the current temperature toa first predetermined temperature range that is provided in a databaseor other memory structure. For example, at decision block 406, thetemperature status reporting engine 206 may determine whether thecurrent temperature is less than or equal to 50° C. If at decision block406 it is determined that the current temperature is not in the firsttemperature range, the method 400 proceeds to decision block 408 whereit is determined whether the current temperature is in a secondtemperature range (e.g., greater than the first temperature T1 but lessthan or equal to a second temperature T2 in the illustrated embodiment).In an embodiment, the temperature status reporting engine 206 in the IHS204 compares the current temperature to a second predeterminedtemperature range that is provided in a database or other memorystructure. For example, at decision block 408, the temperature statusreporting engine 206 may determine whether the current temperature isgreater than 50° C. and less than or equal to 70° C. If at decisionblock 408 it is determined that the current temperature is not in thesecond temperature range, the method 400 proceeds to decision block 410where it is determined whether the current temperature is in a thirdtemperature range (e.g., greater than the second temperature T2 but lessthan or equal to a third temperature T3 in the illustrated embodiment).In an embodiment, the temperature status reporting engine 206 in the IHS204 compares the current temperature to a third predeterminedtemperature range that is provided in a database or other memorystructure. For example, at decision block 408, the temperature statusreporting engine 206 may determine whether the current temperature isgreater than 70° C. and less than or equal to 80° C. If at decisionblock 410 it is determined that the current temperature is not in thethird temperature range, the method 400 proceeds to decision block 412where it is determined whether the current temperature is in a fourthtemperature range (e.g., greater than the third temperature T3 but lessthan or equal to a fourth temperature T4 in the illustrated embodiment).In an embodiment, the temperature status reporting engine 206 in the IHS204 compares the current temperature to a fourth predeterminedtemperature range that is provided in a database or other memorystructure. For example, at decision block 408, the temperature statusreporting engine 206 may determine whether the current temperature isgreater than 80° C. and less than or equal to 85° C.

The method 400 includes a plurality of temperature statuses that may besimilar to the temperature statuses used in the prior art method 300discussed above. In the embodiments discussed below, the specificexamples provided for the first temperature T1, the second temperatureT2, the third temperature T3, the fourth temperature T4, and thetemperature statuses used in the method 400 are the same as those usedin the prior art method 300 in order to illustrate the differences inthe results of operation of the IHS temperature control system 200according to the two methods. However, the first temperature T1, thesecond temperature T2, the third temperature T3, the fourth temperatureT4, and the temperature statuses used in the 400 may be modified basedon the IHSs, IHS components, or any other heat producing devices thatwould benefit from the teachings of the present disclosure.

If, at decision block 406, it is determined that the current temperatureis in the first temperature range (e.g., less than or equal the firsttemperature T1 in the illustrated embodiment)., the method 400 proceedsto decision block 414 where an IHS temperature trend is determined. Inthe illustrated embodiment, the IHS temperature trend of the IHS 204 isdetermined at decision block 414 by determining whether the currenttemperature and the last temperature indicate that the temperature ofthe IHS 204 is increasing or not increasing. In an embodiment, thetemperature status reporting engine 208 in the IHS 204 compares thecurrent temperature determined at block 404 to a last temperature (e.g.,the last temperature set at block 402, a temperature determined during aprevious iteration of the method 400, etc.) to determine whether thetemperature of the IHS 204 is increasing or not increasing (e.g.,whether the current temperature is less than or equal to the lasttemperature in the illustrated embodiment). As discussed in furtherdetail below, the determination of the IHS temperature trend at decisionblock 414 operates to help prevent the cooling system oscillationsassociated with the prior art method 300. If, at decision block 414, itis determined that the current temperature and the last temperatureindicate that the temperature of the IHS 204 is not increasing, themethod 400 proceeds to block 416 where a decrease cooling signal thatcorresponds to a below normal temperature reading is provided by the IHS204 to the chassis management controller 210. In an embodiment, thetemperature status reporting engine 208 provides the decrease coolingsignal (e.g., the first temperature status “TEMP STATUS 1”) to thetemperature control engine 212 in the chassis management controller 210(e.g., upon the current temperature passing the T1 temperaturethreshold, during each iteration of the method 400 in which the currenttemperature is in the first predetermined temperature range, etc.), andin response to provision of the decrease cooling signal, the temperaturecontrol engine 212 is configured to send a signal to the fancontroller(s) in the fan(s) 216 that, for example, operates to decreasethe fan speed of the fan(s) 216 by 4% every 20 seconds. The method 400then proceeds to block 418 where the current temperature determinedduring that iteration of the method 400 is saved as the last temperature(e.g., in a database or other memory structure in the IHS 204), and thenback to block 404 to start the next iteration of the method 400.

If, at decision block 410, it is determined that the current temperatureis in the third temperature range (e.g., greater than the secondtemperature T2 and less than or equal the third temperature T3 in theillustrated embodiment), the method 400 proceeds to decision block 420where an IHS temperature trend is determined. In the illustratedembodiment, the IHS temperature trend of the IHS 204 is determined atdecision block 420 by determining whether the current temperature andthe last temperature indicate that the temperature of the IHS 204 isdecreasing or not decreasing. In an embodiment, the temperature statusreporting engine 208 in the IHS 204 compares the current temperaturedetermined at block 404 to a last temperature (e.g., the lasttemperature set at block 402, a temperature determined during a previousiteration of the method 400, etc.) to determine whether the temperatureof the IHS 204 is decreasing or not decreasing (e.g., whether thecurrent temperature is greater than or equal to the last temperature inthe illustrated embodiment). As discussed in further detail below, thedetermination of the IHS temperature at decision block 420 operates tohelp prevent the cooling system oscillations associated with the priorart method 300. If, at decision block 420, it is determined that thecurrent temperature and the last temperature indicate that thetemperature of the IHS 204 is not decreasing, the method 400 proceeds toblock 422 where a first increase cooling signal that corresponds to awarning temperature reading is provided by the IHS 204 to the chassismanagement controller 210. In an embodiment, the temperature statusreporting engine 208 provides the first increase cooling signal (e.g.,the third temperature status “TEMP STATUS 3”) to the temperature controlengine 212 in the chassis management controller 210 (e.g., upon thecurrent temperature passing the T2 temperature threshold, during eachiteration of the method 400 in which the current temperature is in thethird predetermined temperature range, etc.), and in response to thatfirst increase cooling signal, the temperature control engine 212 isconfigured to send a signal to the fan controller(s) in the fan(s) 216that, for example, operates to increase the fan speed of the fan(s) 216by 5% every 5 seconds. The method 400 then proceeds to block 418 wherethe current temperature is saved as the last temperature as describedabove, and then back to block 404 to start the next iteration of themethod 400.

If, at decision block 408, it is determined that the current temperatureis in the second temperature range (e.g., greater than the firsttemperature T1 and less than or equal the second temperature T2 in theillustrated embodiment), or if at decision block 414 it is determinedthat the current temperature and the last temperature indicate that thetemperature of the IHS 204 is increasing (e.g., the current temperatureis greater than the last temperature in the illustrated embodiment), orif at decision block 420 it is determined that the current temperatureand the last temperature indicate that the temperature of the IHS 204 isdecreasing (e.g., the current temperature is less than the lasttemperature in the illustrated embodiment), the method 400 proceeds toblock 424 where maintain cooling signal that corresponds to a normaltemperature reading is provided by the IHS 204 to the chassis managementcontroller 210. In an embodiment, the temperature status reportingengine 208 provides the maintain cooling signal (e.g., the secondtemperature status “TEMP STATUS 2”) to the temperature control engine212 in the chassis management controller 210 (e.g., upon the currenttemperature passing the T1 or T2 temperature thresholds, during eachiteration of the method 400 in which the current temperature is in thesecond predetermined temperature range, etc.), and in response to thatmaintain cooling signal, the temperature control engine 212 isconfigured to make no changes to the fan speed of the fan(s) 216.

As discussed in further detail below, the sending of the maintaincooling signal in response to determining at decision blocks 406 and 414that the current temperature is in the first predetermined temperaturerange and the IHS temperature trend is increasing, or in response todetermining at decision blocks 410 and 420 that the current temperatureis in the third temperature range and the IHS temperature trend isdecreasing, helps to prevent the cooling system oscillations associatedwith the prior art method 300. The method 400 then proceeds to block 418where the current temperature is saved as the last temperature asdescribed above, and then back to block 404 to start the next iterationof the method 400.

If, at decision block 412, it is determined that the current temperatureis in the fourth temperature range (e.g., greater than the thirdtemperature T3 and less than or equal the fourth temperature T4 in theillustrated embodiment), the method 400 proceeds to block 426 where asecond increase cooling signal that corresponds to a criticaltemperature reading is provided by the IHS 204 to the chassis managementcontroller 210. In an embodiment, the temperature status reportingengine 208 provides the second increase cooling signal (e.g., the fourthtemperature status “TEMP STATUS 4”) to the temperature control engine212 in the chassis management controller 210 (e.g., upon the currenttemperature passing the T3 temperature threshold, during each iterationof the method 400 in which the current temperature is in the fourthpredetermined temperature range, etc.), and in response to that secondincrease cooling signal, the temperature control engine 212 isconfigured to increase the fan speed of the fan(s) 216 by 20% every 5seconds. As such, the second increase cooling signal provides a secondlevel of increased cooling that is greater than a first level ofincreased cooling provided by the first increase cooling signaldiscussed above. The method 400 then proceeds to block 418 where thecurrent temperature is saved as the last temperature as described above,and then back to block 404 to start the next iteration of the method400.

If, at decision block 412, it is determined that the current temperatureis not the fourth temperature range (i.e., its current temperature isgreater than the fourth temperature T4), the method 400 proceeds toblock 428 where an IHS shutdown signal that corresponds to a shutdowntemperature reading is provided by the IHS 204 to the chassis managementcontroller 210. In an embodiment, the temperature status reportingengine 208 provides the IHS shutdown signal (e.g., the fifth temperaturestatus “TEMP STATUS 5”) to the temperature control engine 212 in thechassis management controller 210 (e.g., upon the current temperaturepassing the T4 temperature threshold, during each iteration of themethod 400 in which the current temperature is greater than the fourthpredetermined temperature range, etc.), and in response to that IHSshutdown signal, the temperature control engine 212 is configured tosend a signal to shut down the IHS 204. The method 400 then proceeds toblock 418 where the current temperature is saved as the last temperatureas described above, and then back to block 404 to start the nextiteration of the method 400.

Referring now to FIG. 4 b, a chart 430 is provided to illustrate how theoperation of the IHS temperature control system 200 according to themethod 400 of FIG. 4 a remedies the issues associated with the prior artmethod 300 discussed above. The chart 430, with reference to the method400 and temperature status control actions discussed above, is providedto illustrate the difference in fan speed behavior during the method 400over the same temperature profile discussed in chart 322. For ease ofcomparison, T1, T2, T3, and T4 of the method 400 are provided as 50° C.,70° C., 80° C., and 85° C., respectively, to correspond to thetemperatures discussed above for the prior art method 300. The chart 430includes a plurality of rows separated into three columns—a temperaturedetermined (e.g., the “current temperature” of the IHS 204 discussedabove), a temperature status provided by the IHS 204 in response to thetemperature determined, and a fan speed (in % PWM) that results when thetemperature status is provided to chassis management controller 210.

With reference to the chart 430 beginning at the first row, the IHS 204is shown in a situation in which the temperature determined is 68° C.,69° C., and 70° C. (i.e., the current temperature of the IHS 204 isdetermined to be greater than 50° C. and less than or equal to 70° C. atdecision block 410) in successive iterations of the method 400, whichresults in the provision of the second temperature status (“TEMP STATUS2”) at block 424. In response, the chassis management controller 210makes no changes to the fan speed of the fans 216, providing for a fanspeed of 30% PWM in the illustrated embodiment.

The IHS 204 then determines temperatures of 71° C. and 72° C. (i.e., thecurrent temperature of the IHS 204 is determined to be greater than 70°C. and less than or equal to 80° C. at decision block 410) in successiveiterations of the method 400, which results in a determination, atdecision block 420 for each iteration, of whether the currenttemperature and the last temperature indicate that the temperature ofthe IHS is not decreasing. Because each of those temperatures (71° C.and 72° C.). indicate that the temperature of the IHS 204 is notdecreasing (from 70° C. and 71° C., respectively), the determination atdecision block 420 in each of those cases results in the provision ofthe third temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for a fan speeds of 35%PWM and 50% PWM in the illustrated embodiment.

The IHS 204 then determines a temperature of 72° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 410) in the followingiteration of the method 400, which results in a determination, atdecision block 420, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not decreasing.Because that temperature (72° C.) indicates that the temperature of theIHS 204 is not decreasing (from the previous temperature of 72° C.), thedetermination at decision block 420 results in the provision of thethird temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for a fan speeds of 80%PWM in the illustrated embodiment.

The IHS 204 then determines a temperature of 71° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 410) in the followingiteration of the method 400, which results in a determination, atdecision block 420, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not decreasing.Because that temperature (71° C.) indicates that the temperature of theIHS 204 is decreasing (from the previous temperature of 72° C.), thedetermination at decision block 420 results in the provision of thesecond temperature status (“TEMP STATUS 2”) to the chassis managementcontroller 210. In response to the provision of the second temperaturestatus, the chassis management controller 210 makes no changes to thefan speed of the fans 216, providing for a fan speed of 80% PWM in theillustrated embodiment. Thus, the determination at blocks 410 and 420that the temperature of the IHS 204 is in an elevated range, but the IHStemperature trend of the IHS 204 is decreasing towards a normal range,results in no more increases in fan speed from 80% PWM.

The chart 430 then illustrates how in successive iterations of themethod 400 the IHS 204 determines temperatures between 70° C. and 51° C.(i.e., the current temperature of the IHS 204 is determined to begreater than 50° C. and less than or equal to 70° C. at decision block408), which results in the provision of the second temperature status(“TEMP STATUS 2”) to the chassis management controller 210. In responseto the provision of the second temperature status, the chassismanagement controller 210 makes no changes to the fan speed of the fans216, providing for a fan speed of 80% PWM in that temperature range inthe illustrated embodiment.

The IHS 204 then goes on to determine temperatures of 50° C., 49° C.,and 48° C. (i.e., the current temperature of the IHS 204 is determinedto be less than or equal to 50° C. at decision block 406) in successiveiterations of the method 400, which results in a determination, atdecision block 414, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not increasing.Because those temperatures (50° C., 49° C., and 48° C.) indicate thatthe temperature of the IHS 204 is not increasing (from 51° C., 50° C.,and 49° C., respectively), the determination at decision block 414results in the provision of the first temperature status (“TEMP STATUS1”) to the chassis management controller 210. In response to theprovision of the first temperature status, the chassis managementcontroller 210 decreases the fan speed of the fans 216 by 4% every 20seconds, providing for fan speeds of 76% PWM, 60% PWM, and 48% PWM in ofthe illustrated embodiment.

The IHS 204 then determines temperatures of 49° and 50° C. (i.e., thecurrent temperature of the IHS 204 is determined to be less than orequal to 50° C. at decision block 406) in successive iterations of themethod 400, which results in a determination, at decision block 414, ofwhether the current temperature and the last temperature indicate thatthe temperature of the IHS is not increasing. Because those temperatures(49° and 50° C.). indicate that the temperature of the IHS 204 isincreasing (from 48° C. and 49° C., respectively), the determination atdecision block 414 results in the provision of the second temperaturestatus (“TEMP STATUS 2”) to the chassis management controller 210. Inresponse to the provision of the second temperature status, the chassismanagement controller 210 makes no changes to the fan speed of the fans216, providing for a fan speed of 48% PWM in each successive iterationin of the illustrated embodiment. Thus, the determination at blocks 406and 414 that the temperature of the IHS 204 is in a below normal range,and that the IHS temperature trend of the IHS 204 is increasing towardsa normal range, results in no more decreases in fan speed from 48% PWM.

The IHS 204 then determines a temperature of 51° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 50° C. andless than or equal to 70° C. at decision block 408), which results inthe provision of the second temperature status (“TEMP STATUS 2”) to thechassis management controller 210. In response to the provision of thesecond temperature status, the chassis management controller 210 makesno changes to the fan speed of the fans 216, providing for a fan speedof 48% PWM in successive iterations in the illustrated embodiment untilthe IHS 204 again determines its temperature is again in the thirdtemperature range or the first temperature range.

As can be seen, the method 400 reduces the amplitude of the oscillationsof the fan speed provided in the prior art method 300 that cause thecooling system to provide too much cooling (e.g., reducing extendedperiods of fan speeds of 100% PWM to 80% PWM in the illustratedembodiment) and too little cooling (e.g., reducing extended periods offan speeds of 30% PWM to 48% PWM in the illustrated embodiment). Thus,the present disclosure provides for control of the cooling system basedon temperature trends of the IHS 204, rather than the passing oftemperature thresholds that result in the deficiencies provided by theprior art method 300 discussed above.

Referring now to FIG. 4 c, a chart 432 is provided to illustrate theoperation of the IHS temperature control system 200 according to themethod 400 of FIG. 4 a. For ease of comparison, T1, T2, T3, and T4 ofthe method 400 are provided as 50° C., 70° C., 80° C., and 85° C.,respectively, to correspond to the temperatures discussed above for theprior art method 300. The chart 430 includes a plurality of rowsseparated into three columns—a temperature determined (e.g., the“current temperature” of the IHS 204 discussed above), a temperaturestatus provided by the IHS 204 in response to the temperaturedetermined, and a fan speed (in % PWM) that results when the temperaturestatus is provided to the chassis management controller 210.

With reference to the chart 432 beginning at the first row, the IHS 204is shown in a situation in which the temperature determined is 68° C.,69° C., and 70° C. (i.e., the current temperature of the IHS 204 isdetermined to be greater than 50° C. and less than or equal to 70° C. atdecision block 410) in successive iterations of the method 400, whichresults in the provision of the second temperature status (“TEMP STATUS2”) to the chassis management controller 210. In response to theprovision of the second temperature status, the chassis managementcontroller 210 makes no changes to the fan speed of the fans 216,providing for a fan speed of 30% PWM in the illustrated embodiment.

The IHS 204 then determines temperatures of 71° C. and 72° C. (i.e., thecurrent temperature of the IHS 204 is determined to be greater than 70°C. and less than or equal to 80° C. at decision block 410) in successiveiterations of the method 400, which results in a determination, atdecision block 420 for each iteration, of whether the currenttemperature and the last temperature indicate that the temperature ofthe IHS is not decreasing. Because each of those temperatures (71° C.and 72° C.). indicate that the temperature of the IHS 204 is notdecreasing (from 70° C. and 71° C., respectively), the determination atdecision block 420 in each of those cases results in the provision ofthe third temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for a fan speeds of 35%PWM and 50% PWM in the illustrated embodiment.

The IHS 204 then determines a temperature of 72° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 410) in the followingiteration of the method 400, which results in a determination, atdecision block 420, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not decreasing.Because that temperature (72° C.) indicates that the temperature of theIHS 204 is not decreasing (from the previous temperature of 72° C.), thedetermination at decision block 420 results in the provision of thethird temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for a fan speed of 70% PWMin the illustrated embodiment.

The IHS 204 then determines a temperature of 71° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 410) in the followingiteration of the method 400, which results in a determination, atdecision block 420, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not decreasing.Because that temperature (71° C.) indicates that the temperature of theIHS 204 is decreasing (from the previous temperature of 72° C.), thedetermination at decision block 420 results in the provision of thesecond temperature status (“TEMP STATUS 2”) to the chassis managementcontroller 210. In response to the provision of the second temperaturestatus, the chassis management controller 210 makes no changes to thefan speed of the fans 216, providing for a fan speed of 70% PWM in theillustrated embodiment. Thus, the determination at blocks 410 and 420that the temperature of the IHS 204 is in an elevated range, but the IHStemperature trend of the IHS 204 is decreasing towards a normal range,results in no more increases in fan speed from 70% PWM.

The IHS 204 then determines a temperature of 72° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 70° C. andless than or equal to 80° C. at decision block 410) in the followingiteration of the method 400, which results in a determination, atdecision block 420, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not decreasing.Because that temperature (72° C.) indicates that the temperature of theIHS 204 is not decreasing (from the previous temperature of 71° C.), thedetermination at decision block 420 results in the provision of thethird temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for a fan speed of 75% PWMin the illustrated embodiment. Thus, following a determination in aprevious iteration of the method 400 that the IHS 204 has a currenttemperature that is in an elevated range but an IHS temperature trendthat is decreasing towards a normal range, an increase in the currenttemperature away from the normal range will result in an increase in fanspeed (e.g., from 70% PWM to 75% PWM in the illustrated embodiment).

The IHS 204 then determines temperatures of 73° C. and 74° C. (i.e., thecurrent temperature of the IHS 204 is determined to be greater than 70°C. and less than or equal to 80° C. at decision block 410) in successiveiterations of the method 400, which results in a determination, atdecision block 420 for each iteration, of whether the currenttemperature and the last temperature indicate that the temperature ofthe IHS is not decreasing. Because each of those temperatures (73° C.and 74° C.) indicate that the temperature of the IHS 204 is notdecreasing (from 72° C. and 73° C., respectively), the determination atdecision block 420 in each of those cases results in the provision ofthe third temperature status (“TEMP STATUS 3”) to the chassis managementcontroller 210. In response to the provision of the third temperaturestatus, the chassis management controller 210 increases the fan speed ofthe fans 216 by 5% every 5 seconds, providing for fan speeds of 90% PWMand 95% PWM in the illustrated embodiment.

The IHS 204 then determines temperatures of 73° C., 72° C., and 71° C.(i.e., the current temperature of the IHS 204 is determined to begreater than 70° C. and less than or equal to 80° C. at decision block410) in the following iterations of the method 400, which results in adetermination, at decision block 420, of whether the current temperatureand the last temperature indicate that the temperature of the IHS is notdecreasing. Because that temperatures (73° C., 72° C., and 71° C.)indicate that the temperature of the IHS 204 is decreasing (from theprevious temperatures of 74° C., 73° C., and 72° C., respectively), thedetermination at decision block 420 results in the provision of thesecond temperature status (“TEMP STATUS 2”) to the chassis managementcontroller 210. In response to the provision of the second temperaturestatus, the chassis management controller 210 makes no changes to thefan speed of the fans 216, providing for fan speeds of 95% PWM in theillustrated embodiment. Thus, the determination at blocks 410 and 420that the temperature of the IHS 204 is in an elevated range, but an IHStemperature trend of the IHS 204 is decreasing towards a normal range,results in no more increases in fan speed from 95% PWM.

The chart 430 then illustrates how in successive iterations of themethod 400 the IHS 204 determine temperatures between 70° C. and 51° C.(i.e., the current temperature of the IHS 204 is determined to begreater than 50° C. and less than or equal to 70° C. at decision block408), which results in the provision of the second temperature status(“TEMP STATUS 2”) to the chassis management controller 210. In responseto the provision of the second temperature status, the chassismanagement controller 210 makes no changes to the fan speed of the fans216, providing for fan speeds of 95% PWM in the illustrated embodiment.

The IHS 204 then goes on to determine temperatures of 50° C., 49° C.,48° C., 47° C., and 46° C. (i.e., the current temperature of the IHS 204is determined to be less than or equal to 50° C. at decision block 406)in successive iterations of the method 400, which result in adetermination, at decision block 414, of whether the current temperatureand the last temperature indicate that the temperature of the IHS is notincreasing. Because those temperatures (50° C., 49° C., 48° C., 47° C.,and 46° C.) indicate that the temperature of the IHS 204 is notincreasing (from 51° C., 50° C., 49° C., 48° C., and 47° C.respectively), the determination at decision block 414 results in theprovision of the first temperature status (“TEMP STATUS 1”) to thechassis management controller 210. In response to the provision of thefirst temperature status, the chassis management controller 210decreases the fan speed of the fans 216 by 4% every 20 seconds,providing for fan speeds of 75% PWM, 59% PWM, 55% PWM, 51% PWM, and 47%PWM in of the illustrated embodiment.

The IHS 204 then determines temperatures of 47° and 48° C. (i.e., thecurrent temperature of the IHS 204 is determined to be less than orequal to 50° C. at decision block 406) in successive iterations of themethod 400, which result in a determination, at decision block 414, ofwhether the current temperature and the last temperature indicate thatthe temperature of the IHS is not increasing. Because those temperatures(47° and 48° C.) indicate that the temperature of the IHS 204 isincreasing (from 46° C. and 47° C., respectively), the determination atdecision block 414 results in the provision of the second temperaturestatus (“TEMP STATUS 2”) to the chassis management controller 210. Inresponse to the provision of the second temperature status, the chassismanagement controller 210 makes no changes to the fan speed of the fans216, providing for a fan speed of 47% PWM in the illustrated embodiment.Thus, the determination at blocks 406 and 414 that the temperature ofthe IHS 204 is in a below normal range, but an IHS temperature trend ofthe IHS 204 is increasing towards a normal range, results in no moredecreases in fan speed from 47% PWM. Thus, following a determination ina previous iteration of the method 400 that the IHS 204 has a currenttemperature that is in a below average range but has a temperature trendthat is decreasing away from a normal range, an increase in the currenttemperature towards the normal range will result in no further decreasesin fan speed (e.g., holding the fan speed at 47% PWM in the illustratedembodiment).

The IHS 204 then goes on to determine temperatures of 47° C. and 46° C.(i.e., the current temperature of the IHS 204 is determined to be lessthan or equal to 50° C. at decision block 406) in successive iterationsof the method 400, which results in a determination, at decision block414, of whether the current temperature and the last temperatureindicate that the temperature of the IHS is not increasing. Becausethose temperatures (47° C. and 46° C.) indicate that the temperature ofthe IHS 204 is not increasing (from 48° C. and 47° C. respectively), thedetermination at decision block 414 results in the provision of thefirst temperature status (“TEMP STATUS 1”) to the chassis managementcontroller 210. In response to the provision of the first temperaturestatus, the chassis management controller 210 decreases the fan speed ofthe fans 216 by 4% every 20 seconds, providing for fan speeds of 43% PWMand 39% PWM in the illustrated embodiment. Thus, following adetermination in a previous iteration of the method 400 that the IHS 204has a current temperature that is in below average range and an IHStemperature trend that is increasing towards the normal range thatresults in no further decreases in fan speed, a decrease in the currenttemperature away from the normal range will result in a decrease in fanspeed (e.g., to a fan speed of 39% PWM in the illustrated embodiment).

The IHS 204 then determines temperatures of 47° C., 48° C., 49° C., and50° C. (i.e., the current temperature of the IHS 204 is determined to beless than or equal to 50° C. at decision block 406) in successiveiterations of the method 400, which results in a determination, atdecision block 414, of whether the current temperature and the lasttemperature indicate that the temperature of the IHS is not increasing.Because those temperatures (47° C., 48° C., 49° C., and 50° C.) indicatethat the temperature of the IHS 204 is increasing (from 46° C., 47° C.,48° C., and 49° C., respectively), the determination at decision block414 results in the provision of the second temperature status (“TEMPSTATUS 2”) to the chassis management controller 210. In response to theprovision of the second temperature status, the chassis managementcontroller 210 makes no changes to the fan speed of the fans 216,providing for fan speeds of 39% PWM in the illustrated embodiment.

The IHS 204 then determines a temperature of 51° C. (i.e., the currenttemperature of the IHS 204 is determined to be greater than 50° C. andless than or equal to 70° C. at decision block 408), which results inthe provision of the second temperature status (“TEMP STATUS 2”) to thechassis management controller 210. In response to the provision of thesecond temperature status, the chassis management controller 210 makesno changes to the fan speed of the fans 216, providing for a fan speedof 39% PWM in the illustrated embodiment until the IHS 204 determinesits temperature is again in the third temperature range or the firsttemperature range.

Similarly as discussed above, the method 400 reduces the amplitude ofthe oscillations of the fan speed provided in the prior art method 300that cause the cooling system to provide too much cooling or too littlecooling, while allowing for reversals in the temperature trend of theIHS after passing into any of the predetermined temperature ranges.Thus, the present disclosure provides for control of the cooling systembased on temperature trends of the IHS 204, rather than the passing oftemperature thresholds that result in the deficiencies provided by theprior art method 300 discussed above.

In some of the embodiments discussed above, the chassis managementcontroller 210 may be updated with a temperature status by the IHS 204during each iteration of the method 400. However, in embodiments wherethe chassis management controller 210 is only updated with a temperaturestatus by the IHS 204 when the current temperature of the IHS 204 passesa temperature threshold, the IHS 204 may track the maximum and minimumtemperatures reached by the IHS after passing outside a normaltemperature range. For example, using the first temperature range (below50° C.), the second temperature range (between 50° C. and 70° C.), andthe third temperature range (between 70° C. and 80° C.) discussed above,the IHS may keep track of the minimum temperature reached after passinginto the first temperature range and before passing back into the secondtemperature range, as well as the maximum temperature reached afterpassing into the third temperature range and before passing back intothe second temperature range. These maximum and minimum temperatures maythen be used to allow the IHS 204 determine when the temperature of theIHS has left the normal temperature range, indicated a trend towardsthat normal temperature range, and then reversed that trend back awayfrom the normal temperature range without having first reentered thatnormal temperature range.

For example, referring to FIG. 5, an embodiment of a method 500 forproviding temperature control according to the teachings of the presentdisclosure is illustrated that is substantially similar to the method400 discussed above but with a few modifications. As such, similarmethod blocks include similar reference numbers. As can be seen by acomparison of the methods 400 and 500, the modifications to the method500 provide that if at decision block 414 it is determined that thecurrent temperature and the last temperature indicate that thetemperature of the IHS 204 is increasing (e.g., the current temperatureis greater than the last temperature in the illustrated embodiment), orif at decision block 420 it is determined that the current temperatureand the last temperature indicate that the temperature of the IHS 204 isdecreasing (e.g., the current temperature is less than the lasttemperature in the illustrated embodiment), the method 400 proceeds toblock 502 where a maintain cooling signal that corresponds to a normaltemperature reading is provided by the IHS 204 to the chassis managementcontroller 210 substantially as described above for block 424. However,in those situations, the method 500 returns to block 404 rather thanupdating the current temperature with the last temperature at block 418as is performed in the method 400.

Thus, in the method 500, when the current temperature of the IHS 204 isin the below normal range (e.g., less than below 50° C.), the lasttemperature is updated with the current temperature as long as thecurrent temperature and the last temperature indicate that thetemperature of the IHS 204 is not increasing. When the currenttemperature and the last temperature then begin to indicate that thetemperature of the IHS 204 is increasing (while in the below normalrange), no further cooling is provided, but the last temperature is notupdated. This ensures that the cooling provided by the cooling system214 is not further decreased until the temperature of the IHS 204 dropsbelow the lowest temperature it reached in the below normal rangewithout leaving that below normal range.

Similarly, in the method 500, when the current temperature of the IHS204 is in the warning range (e.g., between 70° C. and 80° C.), the lasttemperature is updated with the current temperature as long as thecurrent temperature and the last temperature indicate that thetemperature of the IHS 204 is increasing. When the current temperatureand the last temperature then begin to indicate that the temperature ofthe IHS 204 is not increasing (while in the warning range), no furthercooling is provided, but the last temperature is not updated. Thisensures that the cooling provided by the cooling system 214 is notfurther increased until the temperature of the IHS 204 raises above thehighest temperature it reached in the warning range without leaving thatwarning range.

Although illustrative embodiments have been shown and described, a widerange of modification, change and substitution is contemplated in theforegoing disclosure and in some instances, some features of theembodiments may be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the scope of theembodiments disclosed herein.

What is claimed is:
 1. A information handling system (IHS), comprising:a chassis; a temperature sensor that is located in the chassis and thatis configured to measure IHS temperatures; and a temperature statusreporting engine that is coupled to the temperature sensor and that isconfigured to: determine a first IHS temperature measured by thetemperature sensor; determine a second IHS temperature measured by thetemperature sensor subsequent to determining the first IHS temperature;and in response to the second IHS temperature being above a firstpredetermined temperature range, provide an increase cooling signal ifthe first IHS temperature and the second IHS temperature indicate thatan IHS temperature trend is not decreasing, and provide a maintaincooling signal if the first IHS temperature and the second IHStemperature indicate that the IHS temperature trend is decreasing. 2.The IHS of claim 1, wherein the temperature status reporting engine isfurther configured to: in response to the second IHS temperature beingbelow the first predetermined temperature range, provide a decreasecooling signal if the first IHS temperature and the second IHStemperature indicate that the IHS temperature trend is not increasing,and provide a maintain cooling signal if the first IHS temperature andthe second IHS temperature indicate that the IHS temperature trend isincreasing.
 3. The IHS of claim 1, wherein the temperature statusreporting engine is further configured to: in response to the second IHStemperature being within the first predetermined temperature range,provide a maintain cooling signal.
 4. The IHS of claim 1, wherein thesecond IHS temperature being above the first predetermined temperaturerange includes the second IHS temperature being in a secondpredetermined temperature range, and wherein the increase cooling signalis a first increase cooling signal that is configured to provide a firstlevel of increased cooling.
 5. The IHS of claim 4, wherein thetemperature status reporting engine is further configured to: inresponse to the second IHS temperature being in a third predeterminedtemperature range that is greater than the second predeterminedtemperature range, provide a second increase cooling signal that isconfigured to provide a second level of increased cooling that isgreater than the first level of increased cooling.
 6. The IHS of claim5, wherein the temperature status reporting engine is further configuredto: in response to the second IHS temperature being above the thirdpredetermined temperature range, provide an IHS shutdown signal.
 7. Aninformation handling system (IHS) temperature control system,comprising: a cooling system; a controller coupled to the coolingsystem; and an IHS coupled to the controller, wherein the IHS includes atemperature status reporting engine that is configured to: determine afirst temperature of the IHS; determine a second temperature of the IHSsubsequent to determining the first temperature; and in response to thesecond temperature being above a first predetermined temperature range,provide a first signal to the controller to increase cooling provided bythe cooling system if the first temperature and the second temperatureindicate that a temperature trend of the IHS is not decreasing, andprovide a second signal to the controller to maintain cooling providedby the cooling system if the first temperature and the secondtemperature indicate that the temperature trend of the IHS isdecreasing.
 8. The IHS temperature control system of claim 7, whereinthe temperature status reporting engine is further configured to: inresponse to the second temperature being below the first predeterminedtemperature range, provide a third signal to the controller to decreasecooling provided by the cooling system if the first temperature and thesecond temperature indicate that the temperature trend of the IHS is notincreasing, and provide the second signal to the controller to maintaincooling provided by the cooling system if the first temperature and thesecond temperature indicate that the temperature trend of the IHS isincreasing.
 9. The IHS temperature control system of claim 7, whereinthe temperature status reporting engine is further configured to: inresponse to the second temperature being within the first predeterminedtemperature range, provide the second signal to the controller tomaintain cooling provided by the cooling system.
 10. The IHS temperaturecontrol system of claim 7, wherein the second temperature being abovethe first predetermined temperature range includes the secondtemperature being in a second predetermined temperature range, andwherein the first signal to the controller provides a first level ofincreased cooling by the cooling system.
 11. The IHS temperature controlsystem 10, wherein the temperature status reporting engine is furtherconfigured to: in response to the second temperature being in a thirdpredetermined temperature range that is greater than the secondpredetermined temperature range, provide a third signal to thecontroller to provide a second level of increased cooling by the coolingsystem that is greater than the first level of increased cooling. 12.The IHS temperature control system of claim 11, wherein the temperaturestatus reporting engine is further configured to: in response to thesecond temperature being above the third predetermined temperaturerange, provide a fourth signal to the controller to shut down the IHS.13. The IHS temperature control system of claim 7, wherein the IHS isone of a plurality of IHSs that are each coupled to the controller andthat each include the temperature status reporting engine, and whereinthe controller is configured to compare the plurality of signalsreceived from each of the plurality of IHSs and to control the coolingsystem based on at least one signal of those plurality of signals thatis associated with the highest temperature.
 14. A method for providingtemperature control, comprising: determining a first temperature of aninformation handling system (IHS); determining a second temperature ofthe IHS subsequent to determining the first temperature; and in responseto the second temperature being above a first predetermined temperaturerange, providing a first signal to a controller to increase coolingprovided by a cooling system if the first temperature and the secondtemperature indicate that a temperature trend of the IHS is notdecreasing, and providing a second signal to the controller to maintaincooling provided by the cooling system if the first temperature and thesecond temperature indicate that the temperature trend of the IHS isdecreasing.
 15. The method of claim 14, further comprising: in responseto the second temperature being below the first predeterminedtemperature range, providing a third signal to the controller todecrease cooling provided by the cooling system if the first temperatureand the second temperature indicate that the temperature trend of theIHS is not increasing, and proving the second signal to the controllerto maintain cooling provided by the cooling system if the firsttemperature and the second temperature indicate that the temperaturetrend of the IHS is increasing.
 16. The method of claim 14, furthercomprising: in response to the second temperature being within the firstpredetermined temperature range, providing the second signal to thecontroller to maintain cooling provided by the cooling system.
 17. Themethod of claim 14, wherein the second temperature being above the firstpredetermined temperature range includes the second temperature being ina second predetermined temperature range, and wherein the first signalto the controller provides a first level of increased cooling by thecooling system.
 18. The method of claim 17, further comprising: inresponse to the second temperature being in a third predeterminedtemperature range that is greater than the second predeterminedtemperature range, providing a third signal to the controller to providea second level of increased cooling by the cooling system that isgreater than the first level of increased cooling.
 19. The method ofclaim 18, further comprising: in response to the second temperaturebeing above the third predetermined temperature range, providing afourth signal to the controller to shut down the IHS.
 20. The method ofclaim 14, further comprising: comparing, by the controller, a pluralityof signals received from each of a plurality of IHSs; and controllingthe cooling system based on at least one signal of those plurality ofsignals that is associated with the highest temperature.